The decimal effect: behavioral and neural bases for a novel influence on intertemporal choice in healthy individuals and in ADHD

A picture is worth a thousand words: Framing of food choice options affects decision conflict and mid-fontal theta in food choice task

In food choices, conflict arises when choosing between a healthy, but less tasty food item and a tasty, but less healthy food item. The underlying assumption is that people trade-off the health and taste properties of food items to reach a decision. To probe this assumption, we presented food items either as colored images (image condition, e.g. photograph of a granola bar) or as pre-matched percentages of taste and health values (text condition, e.g., 20% healthy and 80% tasty). We recorded choices, response times and electroencephalography activity to calculate mid-frontal theta power as a marker of conflict. At the behavioral level, we found higher response times for healthy compared to unhealthy choices, and for difficult compared to easy decisions in both conditions, indicating the experience of a decision conflict. At the neural level, mid-frontal theta power was higher for healthy choices than unhealthy choices and difficult choices compared to easy choices, but only in the image condition. Those results suggest that either conflict type and/or decision strategies differ between the image and text conditions. The present results can be helpful in understanding how dietary decisions can be influenced towards healthier food choices.

Positive autobiographical memory recall does not influence temporal discounting: an internal meta-analysis of experimental studies

People tend to discount the value of future rewards as the delay to receiving them increases. This phenomenon, known as temporal discounting, may underlie many impulsive behaviors, such as drug abuse and overeating. Given the potential role of temporal discounting in maladaptive behaviors, many efforts have been made to find experimental manipulations that reduce temporal discounting. One class of manipulations that has held some promise involves recalling positive autobiographical memories prior to making intertemporal choices. Just as imagining positive future events has been shown to reduce temporal discounting, a few studies have shown that recalling positive past events reduces temporal discounting, especially if memory retrieval evokes positive affective states, such as gratitude and nostalgia. However, we failed to replicate these findings. Here we present an internal meta-analysis combining data from 14 studies (n = 758) that involved within-subjects positive memory recall-based manipulations. In each study, temporal discounting was assessed using a monetary intertemporal choice task. The average effect size was not significantly different from zero. This finding helps elucidate the neurocognitive mechanisms of temporal discounting; whereas engaging the episodic memory system to imagine future events might promote more patience, engaging the episodic memory system to imagine past events does not.

Relationship between an inconsistent degree of financial literacy and inconsistent decision-making in intertemporal choices

Intertemporal choice refers to the decision-making process involving trade-offs between rewards available at different points in time (such as choosing between smaller immediate rewards versus larger rewards later on). Empirical evidence often deviates from the exponential preferences predicted by the normative model. A hyperbolic discount function better mirrors individual behavior, explaining temporal inconsistency - whereby preferences vary over time by applying a higher discount in the present. Hyperbolic preferences are associated with addictive behaviors, such as smoking and alcohol consumption, as well as depression or attention deficit hyperactivity disorder. Established measures in the literature quantify the extent of deviation from exponential trend exhibited by hyperbolic preferences. In addition to behavioral and cognitive factors, it is essential to incorporate financial literacy into the examination of individual decision-making behaviors. The present study analyzes the relationship between the degree of decision-making inconsistency and the degree of financial literacy inconsistency across three dimensions: knowledge, behavior, and attitudes. It aims to illustrate while financial literacy is important, it is not sufficient to ensure rational choices. Rather, it reveals a strong correlation among its dimensions. The results of this research could be included when creating investor profiles required by MiFID, considering insights from behavioral finance studies in these profiles. What is more, understanding psychological biases that can influence financial decision-making empowers investors to make more informed decisions and avoid common pitfalls.

ADHD and the Choice of Small Immediate Over Larger Delayed Rewards: A Comparative Meta-Analysis of Performance on Simple Choice-Delay and Temporal Discounting Paradigms

Objective: Impulsive choices can lead to suboptimal decision making, a tendency which is especially marked in individuals with ADHD. We compared two different paradigms assessing impulsive choice: the simple choice paradigm (SCP) and the temporal discounting paradigm (TDP). Method: Random effects meta-analyses on 37 group comparisons (22 SCP; 15 TDP) consisting of 3.763 participants (53% ADHD). Results: Small-to-medium effect sizes emerged for both paradigms, confirming that participants with ADHD choose small immediate over large delayed rewards more frequently than controls. Moderation analyses show that offering real rewards in the SCP almost doubled the odds ratio for participants with ADHD. Conclusion: We suggest that a stronger than normal aversion toward delay interacts with a demotivating effect of hypothetical rewards, both factors promoting impulsive choice in participants with ADHD. Furthermore, we suggest the SCP as the paradigm of choice due to its larger ecological validity, contextual sensitivity, and reliability.

Delay discounting abnormalities are seen in first-episode schizophrenia but not in bipolar disorder

Delay discounting (DD) is the phenomenon of individuals discounting future rewards as a function of time. It has been studied extensively in chronic schizophrenia (SZ) and the results of these studies have been variable. Comorbidity in chronic samples could be one reason for the mixed findings and studies in first-episode (FE) samples are surprisingly lacking. Bipolar disorder (BP) which shares some genetic and symptom features with SZ could serve as an interesting comparison group for DD but has been underexplored. Here we present the first study that combines FE SZ, FE BP with psychotic features, as well as healthy controls and study DD with two versions of the task. We found that SZ showed steeper discounting than HC and BP on the well-validated Kirby DD task. SZ showed no difference than HC on a separate DD task with smaller rewards presented with decimal places and shorter delays. As a preliminary finding, DD was found to be positively related to positive symptoms in FE SZ, while no relationship was found between negative symptoms and DD. In addition, we found comparable DD in BP compared to HC. Ultimately, our data may help elucidate the psychopathology in SZ and BP during intertemporal decision making.

Behavioral trainings and manipulations to reduce delay discounting: A systematic review

In everyday decision-making, individuals make trade-offs between short-term and long-term benefits or costs. Depending on many factors, individuals may choose to wait for larger delayed reward, yet in other situations they may prefer the smaller, immediate reward. In addition to within-subject variation in the short-term versus long-term reward trade-off, there are also interindividual differences in delay discounting (DD), which have been shown to be quite stable. The extent to which individuals discount the value of delayed rewards turns out to be associated with important health and disorder-related outcomes: the more discounting, the more unhealthy or problematic choices. This has led to the hypothesis that DD can be conceptualized as trans-disease process. The current systematic review presents an overview of behavioral trainings and manipulations that have been developed to reduce DD in human participants aged 12 years or older. Manipulation studies mostly contain one session and measure DD directly after the manipulation. Training studies add a multiple session training component that is not per se related to DD, in between two DD task measurements. Ninety-eight studies (151 experiments) were identified that tested behavioral trainings and manipulations to decrease DD. Overall, results indicated that DD can be decreased, showing that DD is profoundly context dependent and changeable. Most promising avenues to pursue in future research seem to be acceptance-based/mindfulness-based trainings, and even more so manipulations involving a future orientation. Limitations and recommendations are discussed to identify the mechanistic processes that allow for changes in discount rate and behavior accordingly.

Amount and time exert independent influences on intertemporal choice

Intertemporal choices involve trade-offs between the value of rewards and the delay before those rewards are experienced. Canonical intertemporal choice models such as hyperbolic discounting assume that reward amount and time until delivery are integrated within each option prior to comparison1,2. An alternative view posits that intertemporal choice reflects attribute-wise processes in which amount and time attributes are compared separately3-6. Here, we use multi-attribute drift diffusion modelling (DDM) to show that attribute-wise comparison represents the choice process better than option-wise comparison for intertemporal choice in a young adult population. We find that, while accumulation rates for amount and time information are uncorrelated, the difference between those rates predicts individual differences in patience. Moreover, patient individuals incorporate amount earlier than time into the decision process. Using eye tracking, we link these modelling results to attention, showing that patience results from a rapid, attribute-wise process that prioritizes amount over time information. Thus, we find converging evidence that distinct evaluation processes for amount and time determine intertemporal financial choices. Because intertemporal decisions in the lab have been linked to failures of patience ranging from insufficient saving to addiction7-13, understanding individual differences in the choice process is important for developing more effective interventions.

Temporal discounting and attention-deficit/hyperactivity disorder in childhood: reasons for devising different tasks

INTRODUCTION

Temporal discounting (TD) describes how a certain reward is seen as less valuable the more its delivery is postponed. There are two main types of TD tasks, hypothetical and real, both of which use monetary rewards. Over the last few years, however, variants of these tasks have been adjusted to assess clinical groups of children showing impulsivity as found in attention-deficit/hyperactivity disorder (ADHD).

OBJECTIVE

To review and discuss studies conducted over the last 10 years on the use of TD tasks in the assessment of pediatric patients with ADHD.

METHOD

For this literature review, articles were non-systematically selected from PubMed, MEDLINE and SciELO databases to include experimental studies on the use of at least one TD paradigm to assess and distinguish ADHD and non-ADHD groups.

RESULTS

Of the studies assessed, 76.19% used hypothetical tasks, followed by real tasks (28.57%), and, finally, tasks using different types of reward, such as toys or rewarding activities (14.28%).

CONCLUSIONS

Although assessed in few studies, real and alternative tasks appeared to be effective in differentiating clinical groups and suitable for investigating hot executive functions in childhood.

An adaptive, individualized fMRI delay discounting procedure to increase flexibility and optimize scanner time

Research on the rate at which people discount the value of future rewards has become increasingly prevalent as discount rate has been shown to be associated with many unhealthy patterns of behavior such as drug abuse, gambling, and overeating. fMRI research points to a fronto-parietal-limbic pathway that is active during decisions between smaller amounts of money now and larger amounts available after a delay. Researchers in this area have used different variants of delay discounting tasks and reported various contrasts between choice trials of different types from these tasks. For instance, researchers have compared 1) choices of delayed monetary amounts to choices of the immediate monetary amounts, 2) 'hard' choices made near one's point of indifference to 'easy' choices that require little thought, and 3) trials where an immediate choice is available versus trials where one is unavailable, regardless of actual eventual choice. These differences in procedure and analysis make comparison of results across studies difficult. In the present experiment, we designed a delay discounting task with the intended capability of being able to construct contrasts of all three comparisons listed above while optimizing scanning time to reduce costs and avoid participant fatigue. This was accomplished with an algorithm that customized the choice trials presented to each participant with the goal of equalizing choice trials of each type. We compared this task, which we refer to here as the individualized discounting task (IDT), to two other delay discounting tasks previously reported in the literature (McClure et al., 2004; Amlung et al., 2014) in 18 participants. Results show that the IDT can examine each of the three contrasts mentioned above, while yielding a similar degree of activation as the reference tasks. This suggests that this new task could be used in delay discounting fMRI studies to allow researchers to more easily compare their results to a majority of previous research while minimizing scanning duration.

The cart before the horse: When cognitive neuroscience precedes cognitive neuropsychology

Cognitive neuropsychology (CN) has had an immense impact on the understanding of the normal cognitive processes underlying reading, spelling, spoken language comprehension and production, spatial attention, memory, visual perception, and orchestration of actions, through detailed analysis of behavioural performance by neurologically impaired individuals. However, there are other domains of cognition and communication that have rarely been investigated with this approach. Many cognitive neuropsychologists have extended their work in language, perception, or attention by turning to functional neuroimaging or lesion-symptom mapping to identify the neural mechanisms underlying the cognitive mechanisms they have identified. Another approach to extending one's research in CN is to apply the methodology to other cognitive functions. We briefly review the domains evaluated using methods of CN to develop cognitive architectures and computational models and the domains that have used functional neuroimaging and other brain mapping approaches in healthy controls to identify the neural substrates involved in cognitive tasks over the past 20 years. We argue that in some domains, neuroimaging studies have preceded the careful analysis of the cognitive processes underlying tasks that are studied, with the consequence that results are difficult to interpret. We use this analysis as the basis for discussing opportunities for expanding the field.

Dissociable Contributions of Imagination and Willpower to the Malleability of Human Patience

The ability to exercise patience is important for human functioning. Although it is known that patience can be promoted by using top-down control, or willpower, to override impatient impulses, patience is also malleable-in particular, susceptible to framing effects-in ways that are difficult to explain using willpower alone. So far, the mechanisms underlying framing effects on patience have been elusive. We investigated the role of imagination in these effects. In a behavioral experiment (Experiment 1), a classic framing manipulation (sequence framing) increased self-reported and independently coded imagination during intertemporal choice. In an investigation of neural responses during decision making (Experiment 2), sequence framing increased the extent to which patience was related to activation in brain regions associated with imagination, relative to activation in regions associated with willpower, and increased functional connectivity of brain regions associated with imagination, but not willpower, relative to regions associated with valuation. Our results suggest that sequence framing can increase the role of imagination in decision making without increasing the exertion of willpower.

Simulating future value in intertemporal choice

The laboratory study of how humans and other animals trade-off value and time has a long and storied history, and is the subject of a vast literature. However, despite a long history of study, there is no agreed upon mechanistic explanation of how intertemporal choice preferences arise. Several theorists have recently proposed model-based reinforcement learning as a candidate framework. This framework describes a suite of algorithms by which a model of the environment, in the form of a state transition function and reward function, can be converted on-line into a decision. The state transition function allows the model-based system to make decisions based on projected future states, while the reward function assigns value to each state, together capturing the necessary components for successful intertemporal choice. Empirical work has also pointed to a possible relationship between increased prospection and reduced discounting. In the current paper, we look for direct evidence of a relationship between temporal discounting and model-based control in a large new data set (n = 168). However, testing the relationship under several different modeling formulations revealed no indication that the two quantities are related.

Attention-Deficit/Hyperactivity Disorder and Monetary Delay Discounting: A Meta-Analysis of Case-Control Studies

BACKGROUND

A growing number of studies have investigated delay discounting, a behavioral economic index of impulsivity, and its relevance to attention deficit hyperactivity disorder (ADHD), but with mixed findings. The current meta-analysis synthesizes the literature on the relationship between monetary delay discounting and ADHD in studies using case-control designs. Specifically, the objectives were: 1) to characterize the aggregated differences in monetary delay discounting between individuals with ADHD (cases) and controls in studies using categorical case-control designs; 2) to examine potential differences based on sample age (<18 vs. >18), reward outcome (real vs. hypothetical), and prevalence of conduct disorder and oppositional defiant disorder in the sample; and 3) to evaluate potential small-study (publication) bias in the literature.

METHODS

From 567 candidate articles, 21 independent investigations yielded 25 case-control comparisons (total N=3,913). Random effects meta-analysis was conducted using Cohen's d as the common effect size. Publication bias was evaluated using fail-safe N, Begg-Mazumdar and Egger tests, and metaregression of publication year and effect size.

RESULTS

Across studies, a statistically significant difference of medium magnitude effect size was present for the case-control comparisons (d=0.43; p < 10-15). No significant differences based on sample age, reward outcome, or comorbid status was detected. Minimal heterogeneity and evidence of publication bias was present.

CONCLUSIONS

These findings provide robust evidence that delay discounting is significantly elevated among individuals with ADHD compared to controls. Gaps in the literature and the importance of characterizing the neural and genetic bases of this relationship are discussed.

Context influences decision-making in boys with attention-deficit/hyperactivity disorder: A comparison of traditional and novel choice-impulsivity paradigms

Attention-deficit/hyperactivity disorder (ADHD) is characterized by an impaired ability to maintain attention and/or hyperactivity/impulsivity. Impulsivity is frequently defined as the preference for small, immediate rewards over larger, delayed rewards, and has been associated with a variety of negative outcomes such as risky behavior and academic difficulty. Extant studies have uniformly utilized the traditional paradigm of presenting two response choices, which limits the generalization of findings to scenarios in which children/adolescents are faced with dichotomous decisions. The current study is the first to examine the effect of manipulating the number of available response options on impulsive decision-making in boys with and without ADHD. A total of 39 boys (ADHD = 16, typically developing [TD] = 23) aged 8-12 years completed a traditional two-choice impulsivity task and a novel five-choice impulsivity task to examine the effect of manipulating the number of choice responses (two vs five) on impulsive decision-making. A five-choice task was utilized as it presents a more continuous array of choice options when compared to the typical two-choice task, and is comparable given its methodological similarity to the two-choice task. Results suggested that boys with ADHD were significantly more impulsive than TD boys during the two-choice task, but not during the five-choice task. Collectively, these findings suggest that ADHD-related impulsivity is not ubiquitous, but rather dependent on variation in demands and/or context. Further, these findings highlight the importance of examining ADHD-related decision-making within the context of alternative paradigms, as the exclusive utilization of two-choice tasks may promote inaccurate conceptualizations of the disorder.

The Malleability of Intertemporal Choice

Intertemporal choices are ubiquitous: people often have to choose between outcomes realized at different times. Although it is generally believed that people have stable tendencies toward being impulsive or patient, an emerging body of evidence indicates that intertemporal choice is malleable and can be profoundly influenced by context. How the choice is framed, or the state of the decision-maker at the time of choice, can induce a shift in preference. Framing effects are underpinned by allocation of attention to choice attributes, reference dependence, and time construal. Incidental affective states and prospection also influence intertemporal choice. We advocate that intertemporal choice models account for these context effects, and encourage the use of this knowledge to nudge people toward making more advantageous choices.

Neuroanatomic and cognitive abnormalities in attention-deficit/hyperactivity disorder in the era of 'high definition' neuroimaging

The ongoing release of the Human Connectome Project (HCP) data is a watershed event in clinical neuroscience. By attaining a quantum leap in spatial and temporal resolution within the framework of a twin/sibling design, this open science resource provides the basis for delineating brain-behavior relationships across the neuropsychiatric landscape. Here we focus on attention-deficit/hyperactivity disorder (ADHD), which is at least partly continuous across the population, highlighting constructs that have been proposed for ADHD and which are included in the HCP phenotypic battery. We review constructs implicated in ADHD (reward-related processing, inhibition, vigilant attention, reaction time variability, timing and emotional lability) which can be examined in the HCP data and in future 'high definition' clinical datasets.

A dual-systems perspective on addiction: contributions from neuroimaging and cognitive training

Dual-systems theories explain lapses in self-control in terms of a conflict between automatic and deliberative modes of behavioral control. Numerous studies have now tested whether the brain areas that control behavior are organized in a manner consistent with dual-systems models. Brain regions directly associated with the mesolimbic dopamine system, the nucleus accumbens and ventromedial prefrontal cortex in particular, capture some of the features assumed by automatic processing. Regions in the lateral prefrontal cortex are more closely linked to deliberative processing and the exertion of self-control in the suppression of impulses. While identifying these regions crudely supports dual-systems theories, important modifications to what constitutes automatic and deliberative behavioral control are also suggested. Experiments have identified various means by which automatic processes may be sculpted. Additional work decomposes deliberative processes into component functions such as generalized working memory, reappraisal of emotional stimuli, and prospection. The importance of deconstructing dual-systems models into specific cognitive processes is clear for understanding and treating addiction. We discuss intervention possibilities suggested by recent research, and focus in particular on cognitive training approaches to bolster deliberative control processes that may aid quit attempts.